This invention relates to a conveyor furnace; a heating means provides a hot zone, and a continuous conveyor conveys articles through the hot zone.
Conveyor furnaces are used in the heat treatment of articles being produced on a mass production basis, for example in the annealing of pieces of copper tube in the manufacture of copper pipe fittings. The articles are introduced to the conveyor whereon they are carried through the hot zone and thereafter discharged. In this method of heat treatment, the determination of practical values for the temperature of the hot zone and the speed of the conveyor is known; and these values can be determined by trial. Known conveyor furnaces, particularly those intended for the heat treatment of relatively small articles such as the pieces of copper tube mentioned above, include a conveyor having a continuous belt of metal mesh or like flexible structure with interlinked elements. The top run of the belt carries the articles through a furnace chamber while the bottom run of the belt returns below the furnace chamber. In other known conveyor furnaces, the conveyor is a roller conveyor; alternatively the conveyor is an overhead type in which case the articles are suspended.
In general, known conveyor furnaces suffer from disadvantages caused by the fact that several load bearing mechanical components of the furnace are subjected to the conditions of the hot zone; these furnaces tend to be bulky and their thermal efficiency is relatively low.
Some of the mechanical components of the known conveyor furnaces are continuously in the hot zone and have a reduced operational life as a result. Others of such components, for example the flexible belt, enter the hot zone intermittently and therefore experience temperature fluctuation which not only reduces operational life, but also contributes to overall thermal inefficiency of the furnace. The bulkiness of the known conveyor furnaces is largely attributable to their length required for attainment of the desired heat treatment temperature.
The present invention seeks to obviate or mitigate the disadvantages outlined above.